Tear string opening system for flexible container

ABSTRACT

An improved opening system for use with flexible containers includes a lower layer which features a weakened line, and an upper layer, between which is included a tear string positioned in close proximity to the weakened line, the tear string being designed to tear through the upper unweakened layer, and thereby exposing the weakened lower layer. The lower layer is then opened through a bursting action along the weakened line, thereby fully opening the container.

FIELD OF THE INVENTION

The present invention relates to opening systems for flexiblecontainers, specifically to opening systems that allow a container to beopened easily without the use of a secondary cutting implement. Theinvention also relates to the method of making such opening systems andthe apparatus utilized in carrying out such method.

BACKGROUND OF THE INVENTION

Flexible containers, such as bags for food products and the like must betightly closed during storage, shipping and handling. Once delivered tothe end user, the container must be opened to remove the contents. It istherefore advantageous for a container to provide secure containmentwhile also being able to be easily opened without the need for cuttingimplements or complicated procedures.

Containers that are designed to open without cutting tools typicallyincorporate a tear string or a tear strip which is designed to tearalong a predetermined path. In many of these systems, a tear string isincorporated into the plastic coated layer which is typically located onthe inside side of the container construction material. U.S. Pat. Nos.4,629,071, 4,650,079, and 5,375,930 all issued to Tani and U.S. Pat. No.3,276,669 issued to Vilutis, describe opening systems that include atear string heat sealed or fused to the plastic coated layer located onthe inside side of the container construction material. These containersare typically made of a frangible material that allows the string totear through the material thereby providing access to the contents.However, in instances wherein the container materials are less frangibleor wherein the container is made of multiple layer materials that havedifferent tear characteristics, more elaborate tear string systems havebeen incorporated to control the direction of the tear. U.S. Pat. Nos.4,795,035, 5,035,328 and 5,035,329 all issued to Kim, include tearguides incorporated into the design which help to control the directionof the tear. U.S. Pat. No. 5,203,634 issued to Kim incorporatesadditional tear guides located on both sides of the containerconstruction material to further direct the path of the tear strip. U.S.Pat. No. 3,057,539 issued to Leary describes a tear string laminatedinto the plastic coating applied to the inside layer of the containerconstruction material, or, between one layer of a paper based materialand a layer of a foil based material. The specification describes anopening sequence wherein the tear string will tear only the layer(s)above the string, leaving either the plastic coating or the plasticcoating and a layer of foil material left on the container that mayrequire opening through a secondary action. The described system willwork only with container construction materials that include a thin,frangible layer or layers that remain in place after the tear string isremoved. A major limitation with this design will be evident if thesystem is employed in a container that incorporates a strongerconstruction material that would be left in place after the tear stringis removed, in which case, a more positive opening system must beincluded to allow complete opening of the container.

U.S. Pat. No. 4,773,541 issued to Riddell, U.S. Pat. No. 5,135,790issued to Kaplan, U.S. Pat. No. 5,836,697 issued to Chiesa and U.S. Pat.No. 6,354,739 issued to Sheehan describe tape based designs wherein aportion of a tape material along with a section of the container isremoved to provide an opening system for a flexible container. U.S. Pat.No. 6,060,095 issued to Scrimager discloses an opening system wherein asection of the face portion of a bag tears out along a double set ofweakened lines to provide access to the contents.

Although the structures previously defined perform the opening functionsfor which they were designed, the described systems typically complicatethe container manufacturing process due to the multiple opening elementsinvolved. In addition, the systems may be ineffective when used withdifficult to tear materials such as multiple layer material, or, insituations wherein the container is used in a heated environment such asa microwave oven, the string and/or other opening components maydelaminate from the inside of the container construction material. Inother applications, the adhesive or laminating materials used to bondthe tear string to the container construction material may beinappropriate, especially in cases wherein the container is to be usedwith food products. What has not been shown in the prior art is anopening system that can safely and effectively open a container whilebeing simple and inexpensive to manufacture.

BRIEF SUMMARY OF THE INVENTION

The object of the present invention is to provide an end user with anovel and efficient means of opening a container while also providing anopening system that can be produced at low cost. The invention describesa container opening system made of composite material which includes atear string located between two or more material layers, the tear stringrunning in the same direction and in close proximity to a line ofweakness which is provided in the lower layer. (To clarify the positionof the layers, the lower layer will represent the layer located closestto the inside of the container while the upper layer will represent thelayer toward the outside of the container). The system allows the stringto tear through the upper, unweakened layer while leaving the weakenedlower layer in place. The user will then open the weakened lower layerin a secondary action to fully open the container.

The opening system is included in a composite material which comprisestwo or more layers, a tear string being inserted between the layersduring a lamination process, with the lower layer being weakened in aline running in the same direction and aligned with the path of the tearstring. By placing the tear string between the layers, the tear stringwill need only to create a cutting path in the upper layer and will tendto tear in a straight line due to the adherence of the layers to eachother. In effect, the strength of the bond between the layers will begreater than the resistance of the upper layer to being torn by the tearstring, thereby allowing the tear string to cut through the upper layerin a relatively straight line while leaving the lower layer basicallyintact. As described herein, the line of weakness in the lower layerwould include an area in the layer that has been perforated, cut orotherwise weakened through pressure, heat or other means that wouldestablish a line considerably weaker that the area adjacent to it.

The tear string opening system could be incorporated into a flexiblecontainer in several ways. In a preferred embodiment, the tear stringopening system will be incorporated directly into a composite containerconstruction material, being a part of the container thereof. In asecondary embodiment, it may be advantageous to limit the width of theupper or lower layers, allowing one of the layers to cover only aportion of the other corresponding layer of the container. In anadditional secondary embodiment, the opening system could be provided asa composite tape-like system which could be bonded to the inside of thecontainer material in the event the container is made of a frangiblematerial, or the tape like material including the tear string could beapplied between two separate parts of the container at a seam betweentwo sections. With this embodiment, the tape like material including thetear string would include an adhesive or other bonding agent applied tothe top or bottom of the composite material which would allow thecomposite material to be bonded to the container construction material.

Construction of the tear string opening system will comprise; two ormore supply rolls of material which will represent the upper and lowerlayers, the lower layer passing a device which will create a line ofweakness in the layer, adhesive means combining the layers beingapplied, and a tear string inserted in close proximity and aligned withthe line of weakness. In so doing, the end product will comprise amultiple layer material having a tear string located between the layersand in close proximity and aligned with the line of weakness located inthe lower layer. The material can be coiled onto rolls and stored foruse in container production at a later date or in a preferredembodiment, the multiple layer material can be directly utilized in theconstruction of a container. With this second, preferred embodiment, thelamination of the material and the manufacture of a container areproduced in-line, in a production sequence.

The invention improves the art over previous opening devices byproviding an effective opening system for a container while requiringminimal additional cost, that cost being only the additional cost of atear string. By so doing, the invention will represent a considerablecost advantage over other elaborate container opening systems. Theinvention describes an opening system for a container which includes atear string incorporated between two or more layers of material andwherein the lower layer features a line of weakness in close proximityto the position of the tear string.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 Shows a perspective and exploded view of the constructionmaterial layers including a weakened line in the lower layer and a tearstring located between the two layers.

FIG. 2 Shows a perspective view of the opening system with theconstruction material layers bonded together and showing the position ofa tear string in relation to the weakened line and including theposition of a pull tab

FIG. 3 Shows an end on view of the composite construction material withthe position of a tear string in relation to the weakened line.

FIG. 4 Shows the opening system material in the action of being opened,with the upper layer tearing open while the lower layer including theweakened line remains relatively intact.

FIG. 5 Shows the lower layer being burst after the upper layer is opened

FIG. 6 Shows a production technique including rolls of constructionmaterial, a device for creating a weakened line and a tear string beinginserted during manufacture.

DETAILED DESCRIPTION OF THE INVENTION

As best shown in FIG. 1, FIG. 2 and FIG. 3, composite constructionmaterial A includes lower layer 10, upper layer 11, and tear string 30.Tear string 30 is positioned between the layers with the tear stringlocated in close proximity to a line of weakness 40 featured in lowerlayer 10. For descriptive purposes, upper layer 11 will herein bedesignated as representing the layer that will ultimately be featuredtoward the outside of the container, while lower layer 10 will representthe layer that will ultimately be featured toward the inside of thecontainer. Lower layer 10 and upper layer 11 are bonded together usingadhesive material 25, with tear string 30 located within the adhesivematerial. By locating the tear string within the adhesive material, thetear string will be held in place so that it will preferentially tearthrough the upper layer and resist pulling out from between the layers.Lower layer 10 includes line of weakness 40 which is positioned in closeproximity and aligned with tear string 30. The line of weaknesscomprises a series of perforations, a cut line, a score line, or othertype of weakness created through heat, pressure or other means. Theperforated line shown in the drawings is for illustrative purposes onlyand should not be considered a limiting embodiment. Also, adhesivematerial 25 could be substituted with the use of layers of constructionmaterial which could be bonded together through heat, radio waves or anyother type of adhesion without deviating from the scope of theinvention.

In a preferred embodiment, and as best shown in FIG. 2 and FIG. 4, theend user will instigate the tear by pulling upwards on pull tab 60 whichis cut into composite construction material A and will be located at oneor both ends of the container. Pull tab 60 will include cuts madethrough upper layer 11, lower layer 10 or completely through compositeconstruction material A starting from an end of the container and arepreferably arced or angled toward tear string 30 without cutting throughthe tear string. By lifting pull tab 60, the tab portion of compositeconstruction material A will initially tear in a direction toward tearstring 30, and, being adhered to tear string 30, enable the tear stringto tear through the upper layer of the composite construction materialstarting from the tab end of the container and continuing to the otherend of the container. As best shown in FIG. 4, lower layer 10 willpreferably separate from pull tab 60 and remain in place while tearstring 30 is pulled through upper layer 11. As best shown in FIG. 5,after the tear string is pulled through the upper layer from one end ofthe container to the other, the lower layer is opened along line ofweakness 40 thereby completing the opening of the container. In apreferred but not limiting embodiment, opening the lower layer could bedescribed as being a ‘bursting’ action.

FIG. 6 describes the sequence for producing the composite constructionmaterial which includes: supply roll 81 of upper layer material 11,supply roll 80 of lower layer material 10, adhesive applicationapparatus 90, device 99 which creates a line of weakness in lower layer11, supply roll 70 of tear string 30 and roller devices 95 & 96 whichcompress the materials and the string into composite constructionmaterial A. As the construction material layers travel from theirrespective supply rolls, lower layer 10 is perforated or otherwiseweakened by device 99 in a line running longitudinally with thematerial, adhesive 25 is applied through application apparatus 90, tearstring 30 is inserted adjacent to the weakened area 40 in the lowerlayer and the assembly of materials is compressed by rollers 95 & 96into composite construction material A. It should be understood at thispoint that additional layers of material could be included and that eachmaterial used for the upper and lower layers could further consist ofmultiple layer material without deviating from the scope of theinvention. It should also be understood that the positioning of thematerial rolls is arbitrary and that any sequence that would create thedescribed composite construction material could be utilized.

The aforementioned description includes various details and particularfeatures according to preferred embodiments of the present invention,however, it is to be understood that this is for illustrative purposesonly. Various modifications and adaptations may become apparent to thoseof ordinary skill in the art without departing from the spirit and scopeof the present invention. For example, when describing layers it isunderstood that the construction material may contain two or moreprimary layers along with one or more coating layers, with the tear,string located in a position between the layers that will be the mosteffective in tearing through the layer(s) directly above it. The spiritof the invention is to provide a tear string in an appropriate positionbetween construction material layers which will allow the tear string totear through the upper layer or layers, while featuring a line ofweakness which is located in the lower layer or layers in the area ofthe tear string, the function of which is to allow the upper layer(s) tobe opened by the tear string while the lower layer(s) will open througha secondary action. It should also be understood that the term ‘tearstring’ could include a cord, twine, plastic tear strip, wire or othermaterials that would create a relatively straight, sharp cut in theupper layer. For purposes of clarity, the term tear string is intendedto mean the above mentioned alternatives without deviating from thescope of the invention.

1. A container opening system comprising: At least two layers ofconstruction material which are bonded together, said at least twolayers comprising a lower layer and an upper layer; b) said lower layerhaving a line of weakness running parallel to a running edge of saidlayer, c) a tear string being positioned between said layers, adjacentto and aligned with said line of weakness and fixed to said layersthrough said bonding process, d) said tear string designed to tearthrough said upper layer, e) said lower layer designed to open through asecondary bursting action along said line of weakness.
 2. The containeropening system of claim 1 wherein said construction material includes atab which is cut into one or both ends of said construction material tofacilitate grabbing said tear string.
 3. The container opening system ofclaim 1 wherein said line of weakness is selected from a groupcomprising; a series of perforations, a score line, a thinned line or astructurally weakened line.
 4. The container opening system of claim 1wherein said tear string is selected from a group comprising a tearstring, tear strip, wire or other materials which would create arelatively straight and clean cut in said upper layer.
 5. The containeropening system of claim 1 wherein said lower layer represents a partialcovering of said upper layer.
 6. The container opening system of claim 1wherein said upper layer represents a partial covering of said lowerlayer.